<?php
/**
 * Created by PhpStorm.
 * User: linhongzhao
 * Date: 18-5-12
 * Time: 下午9:34
 */

function array_keys($keys) {
    $arr = [];
    foreach ($keys as $key) {
        if (isset($arr[$key])) {
            $arr[] = $key;
        }
    }
    return $arr;
}

function array_keys_bydiff($keys) {

}

// 产生数组

